366 MEMOIKS OF THE UNIVERSITY OF CALIFORNIA 



The species also represents the extreme specialization of a line of species 

 in which the sinistroventral region is deeply incised or concaved by the sulcus 

 and the dextrodorsal one more or less arched. This series progressively includes 

 C. geminatum, G. schuetti (fig. HH, 2), G. vinctum (fig. HH, 3), G. rosaceum 

 (fig. HH, 4). G. convoluttim (fig. HH, 5), G. helix (fig. HH, 8), and G. cavatum 

 (fig. HH, 10), and culminates in G. distortum (fig. HH, 9). 



Cochlodinium elongatum sp. nov. 



Plate 4, figure 45 ; text figures : 6G, 7 



Description.— The body is long cigar-shaped, its length 3.78 transdiameters at the widest 

 part, \yhieh is anterior. It was enclosed in a cyst only very slightly wider than itself but with 

 a somewhat greater length. The cytoplasm is granular, clear and dull opaline green in color. A 

 few refractive rodlets were present near one end (anterior) and a single large vacuole near 

 the other. 



When this organism was first observed a Cochlodinium-like girdle or furrow followed a spiral 

 course around the body from one end to the other (pi. 4, fig. 45), and the nucleus presented the 

 appearance of a late telophase stage of division, with the chromosomes plainly evident. Shortly 

 after it was first seen the furrow became obliterated and the body divided into two portions 

 (fig. 0. 2). A second division of both nucleus and cytopla.sm took place (fig. 0, 3), followed in 

 a short time by a third division which resulted in the production of eight small bodies within 

 the cyst (fig. 0, 4). Further development did not take place, though it was still held under 

 observation for a .short time when it began to disintegrate. 



A single specimen of this peculiar organism was observed in the plankton at La Jolla and 

 one that was not adequate for clearly determining its systematic position and relationships. Its 

 undoubted girdle, dinoflagellate type of nucleus and peculiar type of division place it witli the 

 dinoflagellates and is deemed important enough to record its occurrence here, leaving further 

 investigation to determine its status more fully. 



A comparison of our figures (fig. 0) and those of Chatton (1906) for Blast odiniiim pruvoii 

 (fig. J) shows a striking similarity between the two forms. In Blast odinium, however, according 

 to Chatton, the body is spirally encircled not by a furrow or girdle but by a series of fine spines, 

 linearly arranged. This diiference would effectively separate the two forms and this separation 

 is further widened by the ensuing development. In Blastodinium the body divides into two 

 portions, and these follow individual lines of development, the body increasing to nearly three 

 times its former size (figs. J, 2, 3, 4), the final result being the production of small Gymnodinium 

 (fig. J, 5). No evidence has been found of a similar division of the body into macroejle and 

 microcyte in our form. It seems then that in spite of close resemblances in form and identity 

 in size these two organisms cannot be considered generieally related. 



I)i]\iENSioxs. — Length, 174/^ ; transdiameter, 46/^ ; length of cyst, 195/*. 



OccuREENCE. — TMs was taken August 10, 1917, in a haul one mile off La 

 Jolla, California, from 50 meters to the surface, and in a surface temperatui'e 

 of 22?5 C. 



Cochlodinium faurei sp. nov. 



Plate 2, figure 25 ; text figure GG, 4 



Diagnosis. — A medium sized species with rotund, subovoidal to ellipsoidal 

 body, its length 1.36 transdiameters; girdle a descending left spiral of two 

 turns, displaced 0.78 transdiameter ; stilcus with apical and antapical loops and 



